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Question

Difficulty: MediumWeakening Arguments

To reduce light-induced degradation of delicate seventeenth-century oil paintings, curators at the Vane Gallery replaced all traditional halogen spotlights with light-emitting diode (LED) fixtures that emit zero ultraviolet radiation. Because ultraviolet rays were previously identified as a chief contributor to varnish oxidation, the curators concluded that overall pigment and varnish breakdown in the gallery's collection will decrease by at least 40 percent over the coming decade. Which of the following statements, if true, most seriously weakens the curators' argument?

  1. A
    The financial savings resulting from lower energy consumption after switching to LED lighting will enable the gallery to expand its collection of seventeenth-century artwork.
  2. The specific spectrum of high-energy visible blue light emitted by the new LED fixtures triggers chemical oxidation in seventeenth-century pigments at rates comparable to ultraviolet radiation.Answer
  3. C
    Controlled laboratory trials indicated that traditional halogen spotlights cause significantly more rapid varnish yellowing than any other conventional incandescent light source.
  4. D
    Environmental humidity fluctuations in art galleries generally present a greater long-term risk to wooden structural supports than light exposure does.
  5. E
    Visitors to the gallery report that paintings illuminated by LED fixtures display greater visual clarity than those previously lit by halogen lamps.

Answer

The argument is most seriously weakened by the statement that high-energy visible blue light emitted by the new LED fixtures triggers chemical oxidation in seventeenth-century pigments at rates comparable to ultraviolet radiation.
The argument concludes that switching from halogen to LED lighting will decrease overall painting degradation by at least 40 percent because LEDs emit no UV radiation. The correct answer points out that the new LED lights emit high-energy visible blue light that causes chemical oxidation at rates comparable to UV light. By showing that the new lighting system introduces a different wavelength of light that causes equivalent damage, it demonstrates that the expected reduction in overall degradation is unlikely to occur.

Step-by-Step Solution

1
Identify the argument's premises and conclusion.
The premises state that halogen lights (which emit UV rays that oxidize varnish) were replaced with LED lights emitting zero UV radiation. The conclusion is that overall pigment and varnish breakdown will drop by at least 40%.
Understanding the logical jump from removing UV radiation to expecting an overall 40% reduction in total breakdown is essential.
2
Identify the unstated assumption or flaw in reasoning.
The curators assume that removing UV radiation will substantially reduce overall breakdown without introducing a new harmful factor or overlooking another major source of light damage from LEDs.
To weaken a causal plan-goal argument, look for evidence that the intervention introduces a new cause of the same problem or fails to address another primary cause.
3
Evaluate the choices to find the statement that undermines the conclusion.
The finding that the new LED lights emit high-energy blue light causing oxidation at rates comparable to UV radiation shows that replacing halogen with LED will not yield the projected 40% drop in damage.
This directly counters the projected decrease by introducing an alternative damaging mechanism inherent to the new LED fixtures.

Key Concept

Weakening Causal and Plan-Goal Arguments by Identifying Side Effects or Alternative Causes
Estimated Time:1m 30s
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Topics

Weakening Arguments

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